Restinga (Reefs)

"Restinga" is a term used to designate the coastal plains covered by marine deposits, resulting from the retreat of ocean levels around 5 thousand years ago, during the Quaternary. Following the retreat, there have been lacustrine and fluvial deposits containing, in part, material originating from the Crystalline Complex escarpments, characteristic in the South and Southeast coasts of Brazil, or from the sandstone of the "Formação Barreiras". These plains are situated within humid tropical climate, with no dry season, and average annual rainfalls of around 1700 - 2000 mm. The largest quantity of nutrients in coastal plains is originating from atmospheric precipitation, being fixated mainly in the vegetable biomass.

The coastal plains might present themselves with quite varied extensions, depending on the retreat of the Crystalline's escarpments. Past marine levels have oscillated in such a way as to cause the sedimentation in different terraces, which are testimony of this alternating depositing. By the action of the tides, the deposit of marine sediments has happened in the form of sandy strips, with some older terraces. Behind these deposits, and between the strips, depressions forming fresh water marshes or swamps might occur.

In the coastal plains' beach line there is a vegetation which is adapted to the salty and sandy conditions under the tidal influences, and denominated halofila-psamofila, with reptilious herbaceous species of ample root systems. After this zone, over more stable strips, there is a dense arboreal bushy vegetation, called "jundu", with many terrestrial bromeliads. Its angular form is characteristic, due to the abrasive action of sand particles on the buds facing the beach. It has an organic layer little developed, with the ground bromeliads performing the role of stabilizers of the sub-stratum and of retention of water and nutrients in the system. In the coast of Rio de Janeiro and Espírito Santo there are thickets formed by arboreal and shrubby species, intercalated by uncovered soil. These are denominated according to the presence of dominant percentages, for instance, "Restinga of Clusia", Myrtaceae and Ericaceae.

Over the sandy strips, depending on their age, there might be an established forest which is less exuberant than the Atlantic Forest, with similar flora, penetration of cerrado elements, few characteristic species and a large quantity of epiphytes. There are forests which are similar to the mountain top forests in coastal escarpments, usually over more recent strips, with many Myrtaceae and terrestrial bromeliads.

In marine terraces, the occurrence of temporarily flooded areas supporting marsh forests is common. Between the strips there are depressions which might be permanently humid, sustaining paludal forests, with few adapted arboreal species and many bromeliads over the drenched soil. In the bays of organic soil, both the paludal forest and mono-specific fields of taboa or water lily appear. This group of formations over the coastal plains establishes a mosaic of variable granulation, which enlarges its biological diversity. The fauna of mammals and birds that occur in the forests over "restingas" is similar to the Atlantic Forest, indicating interactions associated to the temporal and spatial alternatives of nourishing, sheltering and nesting resources. Especially due to the urban occupation of coastal plains, these rainforests associated with the Atlantic domain have few remainders, preserved in Conservation Units.

by Waldir Mantovani